Study On Visual Comfort Enhancement Of Stereoscopic Video Based On Parallax Change Adjustment

With the development of science and technology, the technology of stereoscopic video has made major changes, which have gone through the development process from black and white to color, SD to HD, and now to the three-dimensional video. People are no longer satisfied with the performance of a two-dimensional video and now pursue visual impact and the experience of immersion. The improvement that science and technology bring us has been extended to all aspects of our lives. The technology of stereoscopic video has been widely used not only in the field of entertainment, but also in military defense, industrial buildings, sophisticated testing, virtual reality, medical hygiene and so on. The technology of three-dimensional video brings the enjoyment of senses, and it makes our lives more convenient at the same time. Therefore, the research of stereoscopic video technology is urgent.For the reason that the three-dimensional video technology is not mature and the problem such as stereo video sources are not compatible, the viewers may come along with a variety of physiological anomalies in the process of watching stereoscopic video, such as astringent eye, headache, nausea, even some adverse symptoms like vomiting. As the physiological responses are different from different individuals, these negative reactions may cause permanent damage to human body, which is a major factor of restricting the development of stereoscopic video technology.Extensive researches on stereoscopic video technology show that the main causes of visual fatigue from watching stereoscopic video are in three aspects: external factors, physiological factors and psychological factors. The external factors include stereoscopic display device configuration. The physiological factors include the inconsistency between convergence and focus adjustment, vertical disparity and motion parallax. The psychological factors mainly include the effect of shadows and occlusion. For the factors outside the human visual, optimizing device configuration and upgrading software and hardware performance can be used to increase the viewing comfort. For the physiological factors, the studies focus mainly on the adjustment of inconsistence between convergence and focus adjustment, the reduction of vertical disparity and so on. Few studies are related to the discontinuous change of parallax and parallax adjustment to improve visual comfort.Firstly, this thesis introduces the background of stereoscopic video comfort, the significance of research and the current research work. Then it describes the principles of binocular stereoscopic and the factors of visual fatigue. According to the causes of visual fatigue, two approaches which improve visual comfort of watching stereoscopic video are proposed in this paper. Specific embodiments are as follows:(1) As the changes between disparity and motion vector are discontinuous, the unexpected visual perception will be produced. In the case of the difficulties of sight aggregation, the burden of the viewing by the eyes will be increased, and the visual fatigue will be produced. Therefore, comfort evaluation model is established based on a single video frame and multiple video frames in an inspection period, respectively. By using the motion vector and the disparity vector information of the current frame got from JMVC(Joint Multi-view Video Coding), the video frame which affects the viewing comfort will be found. Using non-comfortable frame parallax adjustment method, the parallax, which is from the video frame affecting the viewing comfort, will be adjusted. Finally, the new video, in which the visual comfort is improved, will be obtained.(2) Suppose most video frames in stereoscopic video, such as a 3D movie, are in the comfort range which are of consistency between convergence and focus adjustment. However, the frames which are outside the range of comfort need to be adjusted. Firstly, the entire stereoscopic video is matched by SIFT(Scale Invariant Feature Transform) algorithm. According to the statistical results, the horizontal parallax and vertical parallax are obtained, and the range of comfort viewing min max[D, D] will be determined. Secondly, the vertical parallax in the video frames will be reduced and the video frames which are not in the range of comfort will be adjusted. Finally, the new video with visual comfort is obtained.Multiple sets of multi-view video sequences are used as experimental video sequence. Subjective comfort evaluation method is used in this thesis. The stereoscopic video before and after processing are subjectively evaluated through several experiments. Experimental results show that the effectiveness of the two methods proposed in this thesis can effectively improve the visual comfort of watching stereoscopic video.